The Effect of Two Novel Lubricant Eye Drops on Tear Film Lipid Layer Thickness in Subjects With Dry Eye Symptoms

PURPOSE: Because the lipid layer of the tear film is recognized as a critical component in dry eye disease, this study was designed to determine if a single eye drop of either Soothe or Systane produces a significant increase in lipid layer thickness (LLT) for subjects reporting symptoms indicative of dry eyes. METHODS: A double-blind, internally paired study was performed. A custom-built lipid layer interferometer, enabling characterization of lipid layer interference patterns, was used to quantify baseline LLT (OU) of eligible subjects. Inclusion criteria included: 1) presence of dry eye symptoms and 2) baseline LLT < or =75 nm. Subjects (n = 40) received a single eye drop of Soothe in one eye and a single eye drop of Systane in the contralateral eye. After the instillation of each test drop, LLT was reanalyzed for all subjects. RESULTS: The mean +/- standard error baseline LLT pre-eye drop instillation was 60.0 +/- 1.8 nm for eyes treated with Soothe and 61.5 +/- 1.8 nm for eyes treated with Systane. These means were not significantly different (p > 0.5). The mean LLT for eyes treated with Soothe increased to 124.4 +/- 4.9 nm (p < 0.0001). The mean LLT for eyes treated with Systane increased to 71.3 +/- 2.6 nm (p < 0.0001). The LLT increase from Soothe was significantly greater than that from Systane (p < 0.0001). CONCLUSIONS: In subjects with symptoms indicative of dry eye states and LLT < or =75 nm, one eye drop of Soothe more than doubled LLT, a 107% mean increase, whereas Systane increased LLT by 16%.